Part 1 of Essay
Coral reefs are one of the oldest types of living systems on earth, and certainly one of the most spectacular. They are massive underwater structures formed by the limestone skeletons of tiny invertebrate animals. Reefs house a greater diversity of body forms, chemistry, and animal phyla (thirty-two compared to the eight t ....

Part 2 of Essay
.... and other debris, to form the backbone of the reef. Over tens of thousands of years, chemical and mechanical changes turn the reef into true rock. The body of a coral animal consists of a polyp, which is the living portion of the coral. A polyp is a hollow, cylindrical structure attached at one end to a surface, the other end is a mouth surrounded by tentacles which gather food and can sting prey to paralyse it. Polyps live in colonies, which grow from 1 to 7 inches, depending on the species. Coral polyps are ....